Gwen, Michael (1837-1913) and Emaline Alewine (1840-1908)married in 1858 in Anderson County, SC, then moved to Arkansas in 1870. Michael's parents were Jacob Alewine (1808-1887) and Margaret Darby (1813-1870). Emaline's parents were Michael Alewine (1811-1845) and Sarah Crowther (1816-1899) Michael and Emiline's fathers, Jacob and Michael, were brothers.
David Calvin (b. abt. 1850) and Angiline Alewine (b. abt 1850) married abt. 1873 in Anderson County, SC. David and Angiline were second cousins. David's father was Joseph A. Alewine (1824-1889) who was the nephew of Angiline's father Jacob Alewine(1808-1887).
James W. (1866-1923)and Mary J. Alewine (1868-1941) married abt. 1883 in Anderson County, SC. James' parents were James Addison Alewine (1843-1911) and Sarah Davis (1842-1915). Mary J. "Mamie Riller" Alewine's parents were Joseph Fields Alewine (1848-1915) and Mary Ann Banister (1843-1891). James Addison Alewine and Joseph Fields Alewine were brothers, sons of Ephraim Alewine (abt 1794-abt 1865).
James A. (1869-1939)and Henrietta Alewine (1871-1932)married abt. 1885 in Anderson County, SC. This James Addison Alewine was the son of Joseph Fields Alewine and Mary Ann Banister and was the nephew of the elder James Addison Alewine mentioned above. Henrietta Alewine was the daughter of the elder James Addison Alewine (1843-1911) and Sarah Davis.
So that means James W. and his sister Henrietta both married their first cousins, Mary J. and James A., who were also brother and sister.